/**
 * Normalize fonts from Google Fonts and Fontshare to unified model
 *
 * Transforms provider-specific font data into a common interface
 * for consistent handling across the application.
 */

import type {
    FontCategory,
    FontProvider,
    FontSubset,
} from '$entities/Font';
import type { FontshareFont } from '$entities/Font';
import type { GoogleFontItem } from './googleFonts';

/**
 * Font variant types (standardized)
 */
export type UnifiedFontVariant = string;

/**
 * Font style URLs
 */
export interface FontStyleUrls {
    /** Regular weight URL */
    regular?: string;
    /** Italic URL */
    italic?: string;
    /** Bold weight URL */
    bold?: string;
    /** Bold italic URL */
    boldItalic?: string;
}

/**
 * Font metadata
 */
export interface FontMetadata {
    /** Timestamp when font was cached */
    cachedAt: number;
    /** Font version from provider */
    version?: string;
    /** Last modified date from provider */
    lastModified?: string;
    /** Popularity rank (if available from provider) */
    popularity?: number;
}

/**
 * Font features (variable fonts, axes, tags)
 */
export interface FontFeatures {
    /** Whether this is a variable font */
    isVariable?: boolean;
    /** Variable font axes (for Fontshare) */
    axes?: Array<{
        name: string;
        property: string;
        default: number;
        min: number;
        max: number;
    }>;
    /** Usage tags (for Fontshare) */
    tags?: string[];
}

/**
 * Unified font model
 *
 * Combines Google Fonts and Fontshare data into a common interface
 * for consistent font handling across the application.
 */
export interface UnifiedFont {
    /** Unique identifier (Google: family name, Fontshare: slug) */
    id: string;
    /** Font display name */
    name: string;
    /** Font provider (google | fontshare) */
    provider: FontProvider;
    /** Font category classification */
    category: FontCategory;
    /** Supported character subsets */
    subsets: FontSubset[];
    /** Available font variants (weights, styles) */
    variants: UnifiedFontVariant[];
    /** URL mapping for font file downloads */
    styles: FontStyleUrls;
    /** Additional metadata */
    metadata: FontMetadata;
    /** Advanced font features */
    features: FontFeatures;
}

/**
 * Map Google Fonts category to unified FontCategory
 */
function mapGoogleCategory(category: string): FontCategory {
    const normalized = category.toLowerCase();
    if (normalized.includes('sans-serif')) {
        return 'sans-serif';
    }
    if (normalized.includes('serif')) {
        return 'serif';
    }
    if (normalized.includes('display')) {
        return 'display';
    }
    if (normalized.includes('handwriting') || normalized.includes('cursive')) {
        return 'handwriting';
    }
    if (normalized.includes('monospace')) {
        return 'monospace';
    }
    // Default fallback
    return 'sans-serif';
}

/**
 * Map Fontshare category to unified FontCategory
 */
function mapFontshareCategory(category: string): FontCategory {
    const normalized = category.toLowerCase();
    if (normalized === 'sans' || normalized === 'sans-serif') {
        return 'sans-serif';
    }
    if (normalized === 'serif') {
        return 'serif';
    }
    if (normalized === 'display') {
        return 'display';
    }
    if (normalized === 'script') {
        return 'handwriting';
    }
    if (normalized === 'mono' || normalized === 'monospace') {
        return 'monospace';
    }
    // Default fallback
    return 'sans-serif';
}

/**
 * Map Google subset to unified FontSubset
 */
function mapGoogleSubset(subset: string): FontSubset | null {
    const validSubsets: FontSubset[] = [
        'latin',
        'latin-ext',
        'cyrillic',
        'greek',
        'arabic',
        'devanagari',
    ];
    return validSubsets.includes(subset as FontSubset)
        ? (subset as FontSubset)
        : null;
}

/**
 * Map Fontshare script to unified FontSubset
 */
function mapFontshareScript(script: string): FontSubset | null {
    const normalized = script.toLowerCase();
    const mapping: Record<string, FontSubset | null> = {
        latin: 'latin',
        'latin-ext': 'latin-ext',
        cyrillic: 'cyrillic',
        greek: 'greek',
        arabic: 'arabic',
        devanagari: 'devanagari',
    };
    return mapping[normalized] ?? null;
}

/**
 * Normalize Google Font to unified model
 *
 * @param apiFont - Font item from Google Fonts API
 * @returns Unified font model
 *
 * @example
 * ```ts
 * const roboto = normalizeGoogleFont({
 *     family: 'Roboto',
 *     category: 'sans-serif',
 *     variants: ['regular', '700'],
 *     subsets: ['latin', 'latin-ext'],
 *     files: { regular: '...', '700': '...' }
 * });
 *
 * console.log(roboto.id); // 'Roboto'
 * console.log(roboto.provider); // 'google'
 * ```
 */
export function normalizeGoogleFont(apiFont: GoogleFontItem): UnifiedFont {
    const category = mapGoogleCategory(apiFont.category);
    const subsets = apiFont.subsets
        .map(mapGoogleSubset)
        .filter((subset): subset is FontSubset => subset !== null);

    // Map variant files to style URLs
    const styles: FontStyleUrls = {};
    for (const [variant, url] of Object.entries(apiFont.files)) {
        if (variant === 'regular' || variant === '400') {
            styles.regular = url;
        } else if (variant === 'italic' || variant === '400italic') {
            styles.italic = url;
        } else if (variant === 'bold' || variant === '700') {
            styles.bold = url;
        } else if (variant === 'bolditalic' || variant === '700italic') {
            styles.boldItalic = url;
        }
    }

    return {
        id: apiFont.family,
        name: apiFont.family,
        provider: 'google',
        category,
        subsets,
        variants: apiFont.variants,
        styles,
        metadata: {
            cachedAt: Date.now(),
            version: apiFont.version,
            lastModified: apiFont.lastModified,
        },
        features: {
            isVariable: false, // Google Fonts doesn't expose variable font info
            tags: [],
        },
    };
}

/**
 * Normalize Fontshare font to unified model
 *
 * @param apiFont - Font item from Fontshare API
 * @returns Unified font model
 *
 * @example
 * ```ts
 * const satoshi = normalizeFontshareFont({
 *     id: 'uuid',
 *     name: 'Satoshi',
 *     slug: 'satoshi',
 *     category: 'Sans',
 *     script: 'latin',
 *     styles: [ ... ]
 * });
 *
 * console.log(satoshi.id); // 'satoshi'
 * console.log(satoshi.provider); // 'fontshare'
 * ```
 */
export function normalizeFontshareFont(apiFont: FontshareFont): UnifiedFont {
    const category = mapFontshareCategory(apiFont.category);
    const subset = mapFontshareScript(apiFont.script);
    const subsets = subset ? [subset] : [];

    // Extract variant names from styles
    const variants = apiFont.styles.map(style => {
        const weightLabel = style.weight.label;
        const isItalic = style.is_italic;
        return isItalic ? `${weightLabel}italic` : weightLabel;
    });

    // Map styles to URLs
    const styles: FontStyleUrls = {};
    for (const style of apiFont.styles) {
        if (style.is_variable) {
            // Variable font - store as primary variant
            styles.regular = style.file;
            break;
        }

        const weight = style.weight.number;
        const isItalic = style.is_italic;

        if (weight === 400 && !isItalic) {
            styles.regular = style.file;
        } else if (weight === 400 && isItalic) {
            styles.italic = style.file;
        } else if (weight >= 700 && !isItalic) {
            styles.bold = style.file;
        } else if (weight >= 700 && isItalic) {
            styles.boldItalic = style.file;
        }
    }

    // Extract variable font axes
    const axes = apiFont.axes.map(axis => ({
        name: axis.name,
        property: axis.property,
        default: axis.range_default,
        min: axis.range_left,
        max: axis.range_right,
    }));

    // Extract tags
    const tags = apiFont.font_tags.map(tag => tag.name);

    return {
        id: apiFont.slug,
        name: apiFont.name,
        provider: 'fontshare',
        category,
        subsets,
        variants,
        styles,
        metadata: {
            cachedAt: Date.now(),
            version: apiFont.version,
            lastModified: apiFont.inserted_at,
            popularity: apiFont.views,
        },
        features: {
            isVariable: apiFont.axes.length > 0,
            axes: axes.length > 0 ? axes : undefined,
            tags: tags.length > 0 ? tags : undefined,
        },
    };
}

/**
 * Normalize multiple Google Fonts to unified model
 *
 * @param apiFonts - Array of Google Font items
 * @returns Array of unified fonts
 */
export function normalizeGoogleFonts(
    apiFonts: GoogleFontItem[],
): UnifiedFont[] {
    return apiFonts.map(normalizeGoogleFont);
}

/**
 * Normalize multiple Fontshare fonts to unified model
 *
 * @param apiFonts - Array of Fontshare font items
 * @returns Array of unified fonts
 */
export function normalizeFontshareFonts(
    apiFonts: FontshareFont[],
): UnifiedFont[] {
    return apiFonts.map(normalizeFontshareFont);
}